Bats developed a reproductive scheme that involved flying, eating insects and hiding in caves during the day that did not involve insurmountable competition from any other species and was adequate for their survival.

After 10 minutes of googling:

Previous studies suggest that many species of insectivorous bats are nocturnal, despite the relatively low availability of their insect prey at night, because of the risk of predation by diurnal predatory birds....In contrast, northern bats (Eptesicus nilssonii), fed mostly between 22:00 and 02:00, coinciding with the lowest aerial insect availability, and with the period when light levels were lowest (ca 1000 lux). Bat activity patterns were closest to those predicted by the avian competition hypothesis....Possibly populations of both species were higher historically and the observed patterns reflected historical competition.

Disappearance of old forests goestogether with disappearing of roosts of forestdwellingbats. Furthermore, deficiency of roostingpossibilities is worsened by the fact thatcompetition between birds and bats may increasewhile numbers of tree holes decrease (Masonet al. 1972).

Birds and bats created different strategies to survive and reproduce which has worked quite well for them. For human convenience we say they occupy niches. In this case, parts of the niches overlap and competition results. Still, from the history of each speciesâ€™ longevity, the schemes each has devised have been adequate to prolong their species for millions of years.

The term â€œnicheâ€ has no effect on the processes involved in evolution. It is a convenient word to use to denote differing survival strategies. Do not let the word constrain your seeing the grander picture.

You typically seem to think survival is an all or nothing situation at every juncture. It isn't. The world is gray.

What survived is what survived, and it may have had as much to do with luck as anything when the asteroid hit.

We don't know if niches were really so empty.

They don't have to be empty for there to be opportunity. I'm sure that when you go shopping for food you don't wait until the store is empty -- you know there is sufficient opportunity to buy what you want or something close enough that you can eat.

Early whales were predators (you noted the jaw of one was like a crocodile eh?). That changes the balance with other predators - wary coexistence is more common than fighting every encounter. Perhaps the early whales survived and thrived because they were hunting rather than being the hunted.

In the warm climate of Eocene I do not see the advantage.

Strangely the world doesn't require your ability to see the advantage for it to have happened. Life is not limited by your inability to see.

The fact that completely non-aquatic deer can drink out of a river without being eaten to extinction, the fact that manatees can live in swamps without being eaten to extinction, and so forth shows that prey animals can coexist in the same environment as predators. In fact, if they couldn't the predators themselves would become extinct. So I see no reason why the transitional forms between, say, pakicetus and modern whales couldn't coexist with crocodiles and sharks; other animals manage to do it.

When they could coexist with Ambulocetus very well in a given niche once why we don't observe evolution of land mammals into aquatic ones after Eocene any more? It was your explanation that mammalian radiation occured because of "emptied niches". If niche could be filled and evolution occured what impeded fishes to go out from water and what impeded land mammals became aquatic animals after Eocene? Evolution should continue with the same pace - if filled niche did not influence evolutionary process during Eocene there is not reason why it should influence it afterwards.

I'm not sure why you think that crocodiles should have grabbed up all the good niches (uh-oh, there's that word again) before ambulocetus had a chance to evolve into them.

They had let say 5.000.000 years to found out all good niches on the shore. But again - after ambulocetus evolved - there were not anymore "emptied niches" afterwards available for evolution of land mammals into aquatic ones during next 30.000.000 years (except Pinnipedia)?

Perhaps the early whales survived and thrived because they were hunting rather than being the hunted.

My point is that they entered environment with fully adapted predators and yet there was enough space and nurture for them too. If the nurture is really no problem as you seems to admit with your "shopping store" story I see no selective pressure in the Nature at all. All development subsequently was a matter of "internal factors" .

The term â€œnicheâ€ has no effect on the processes involved in evolution. It is a convenient word to use to denote differing survival strategies. Do not let the word constrain your seeing the grander picture.

I have just challenged these darwinistic "niche", "natural selection", "survival strategies" words in order to see grander picture without distortion.

My point is that they entered environment with fully adapted predators and yet there was enough space and nurture for them too. If the nurture is really no problem as you seems to admit with your "shopping store" story I see no selective pressure in the Nature at all. All development subsequently was a matter of "internal factors" .

This whole post makes absolutely no sense. I am assuing you were wasted when you wrote this and should be given an opportuninty to repost your point.

Eagerly await the repost.

Doctor Bashir: "Of all the stories you told me, which were true and which weren't?"Elim Garak: "My dear Doctor, they're all true"Doctor Bashir: "Even the lies?"Elim Garak: "Especially the lies"

A young ambulocetus entered the Ocean during Eocene. The Ocean was full of predators at that time. The Ambulocetus was predator too. The father Ocean is always full of foods and delicate meals for all predators. In the Ocean there it's like in the shopping mall. Whenever you came it's open. There's a lot of items to choose. Just enter, please. Father Ocean is waiting for you 24/7/365/Eons to become a predator. Other predators are looking forward to meet you.

quote: It was your explanation that mammalian radiation occured because of "emptied niches".

Was? It still is. The KT-event emptied a lot of niches. There was a lot of opportunity for dramitically new (at least new to the surviving species) ways of utilizing available resources, resources that suddenly became available to the surviving species (but were previously unavailable because they were being utilized by other species that were now extinct).

So, right after the Cretaceous, a series of mutations that would, over time, lead to a profound morphological difference could possibly result in a new viable species.

However, by the late eocene the new opportunities had either been already filled by new species adapting into them, or closed as the new species created new ecosystems where the potential niche could not be realized.

In this situation, natural selection would not, in general, result in profoundly new morphologies. First, because the new species had fully adapted to the newly established ecosystems so that small morphological differences from the average population norm would be less adapted to the lifestyle in which the species had adapted. Second, if the small changes made the individual better adapted to take advantage of a different set of resources, by this time those resources were already being utilized by a better adapted species. So in this case, natural selection would act as a relatively conservative force.

So your reasoning returned back to "empty niche" explanation in this case of whale origin. Never mind, the same can be found at talkorigin:

Before the late-Cretaceous extinctions, the Mesozoic marine reptiles such as the plesiosaurs, ichthyosaurs, mosasaurs, and marine crocodiles might well have feasted upon any mammal that strayed off shore in search of food. Once those predators were gone, the evolution quickly produced mammals, including whales, that were as at home in the seas as they once were on land.

It's really a big misunderestanding that crocodiles "were gone". It's on you which of plesiosaurs, ichthyosaurs, mosasaurs hunted in estuaries - anyway crocs survived and according darwinism should be able to fill emptied niches geometrically. According Talkorigin crocodiles were present with Pakicetus:

Although the mammalian fauna found with Pakicetus consists of rodents, bats, various artiodactyls, perissodactyls and probiscideans, and even a primate (Gingerich and others 1983), there are also aquatic animals such as snails, fish, turtles and crocodilians.

I would say that conception of "empty niche" that Pakicetus filled is more than questionable.

Using the same logic we should explain the stop of transition of other mammals into aquatic species after Eocene like:

"After Eocene marine mammals like dolphins, whales and marine crocodiles might well have feasted upon any mammal that strayed off shore in search of food." Eh,eh.

How do you enter something you are already part of? What do you mean by "fully adapted" - able to survive and breed? Anything else is meaningless because that is all that is required. But this also applies just as strongly to the whale ancestors as to your list of predators.

At every stage of their development from land to water the whale ancestors were fully adapted to the environment they were in.

The only difference between them and the other animals was that generation by generation their environment was a little bit more in the water and a little less on the land.

At every stage of their development from land to water the whale ancestors were fully adapted to the environment they were in.

There were opportunities presented by the environment, opportunities presented by the variations in genetics of their population group and opportunities presented by their behavior.

At every stage of their development from land to water the whale ancestors were fully adapted to the environment they were in.

Evolution does not occur in sudden shifts in individuals, it does not occur within individuals. Evolution is a process of change over time within a population. Those that are better able to survive and breed are the ones that have greater opportunity to survive and breed while those that are NOT better able to survive and breed have less opportunity to do so.

At every stage of their development from land to water the whale ancestors were fully adapted to the environment they were in.

... yet there was enough space and nurture for them too.

At every stage of their development from land to water the whale ancestors were fully adapted to the environment they were in.

All development subsequently was a matter of "internal factors" .

No "internal factors" required. It's like walking down the road. One step at a time gets you there. You don't reach a point where you suddenly need a mythical "internal factor" to take another step.

At every stage of their development from land to water the whale ancestors were fully adapted to the environment they were in.

At every stage of their development from land to water the whale ancestors were fully adapted to the environment they were in.

Might be the more you repeat it the more you are convinced it to be true.

Yet when all of them from Pakicetus, Ambulocetus etc.. were so "fully adapted" why all of them disappeared? Ambulocetus looks like crocodile - why we don't find him today? All ambulocetuses transformed into whales? (And crocodiles refused to transform in the same niche at all?) Ambulocetus evolved into whale and crocodiles remain in the same niche unaltered?

No other branch from Pakicetus has evolved that survived till today? Is it possible that on the cladogram nothing except whales live nowadays (exceopt fully marine mammals)? Is there really no living branch on the cladogram of land-whale transiton when all of them were so fully adapted? Crocodiles were also fully adapted and are fully adapted even today I suppose.

However, Davison's claim is that no new genera have evolved since then.

Obviously you didn't read Davison tretase at all. Anyway Lang supports Broom's idea that evolution of genera and species stagnates in quartenary too:

At the end of the Tertiary the organisms consisted of species, almost all of which can be assigned to present genera, a large section even to living species. This applies not only for the European flora but also for its fauna.

"Despite the environmental conditions for this time period have been characterized as excessively varying, temperatures rising and falling producing among other effects a series of ice ages â€“ and in spite of all these environmental variations there was hardly any evolution at all."